Preliminary assessments of the anti-roll tank as a wave energy converter

Abstract

Wave energy is the largest renewable energy resource. To explore the approximate quantities of energy extraction, an anti-roll tank developed for reducing the excessive ship rolling was introduced into a type of wave energy converter (WEC). From a view of energy interaction, the interior liquid of tank absorbs part wave energy and converts to fluid kinetic energy, and this energy may exploit to generate electricity. Based on anti-roll tank technology, this study assessed the production of a particular amount of exploitable energy. A passive U-tube tank was chosen and a ship-form carrier was selected from a small craft. The liquid equation in the tank is coupled with the 5DOF equations of carrier's motion. A subroutine for integrating the tank equation is added to the non-linear strip synthesis, and all of the equations are integrated simultaneously and interactively within the time domain. Transformation efficiency is introduced to measure the percentage of power transformation. The result of the regular wave tests shows that the optimal transformation percentage occurs near the tank's natural frequency. If operating at sea, the average transformation efficiency of the proposed device is approximately 4.83%. It can be regarded as a potential device and needs further investigation.

Keywords:

• passive U-tube tank
• wave energy converter
• transformation efficiency

Acknowledgements

The author would like to express his deep appreciation to Dr. Chiu Forng-Chen, the president of Ship and Ocean Industries R&D Center (SOIC), for offering the inspiring insights to the present study.